Various satellite-based navigation systems such as the Global Positioning System (GPS) and Global Navigation Satellite System (GNSS) have been utilized by individual users for navigation. For example, satellite-based navigation devices, which may be either stand-alone devices or integrated as part of handheld mobile telephones or tablets, have been used by individuals who need navigation instructions as drivers or pedestrians. Satellite based navigation systems have also been provided as integral parts of motor vehicles. A typical navigation device is capable of not only indicating the current position, but also providing recommended routes, turn-by-turn instructions, and expected time of travel, and so on, based on signals received from navigation satellites as well as digital maps and road information stored in the memory or storage medium of the navigation device.
A conventional navigation device typically requires nearly constant good reception of satellite-based navigation signals for updating the current position of the device on the map. Good reception of satellite-based navigation signals, however, is not guaranteed in all environments. For example, in close proximity to tall buildings or other obstructions, GPS or GNSS signals are often degraded due to reflections, attenuations or multipath effects. When a user is inside a building with walls, beams, and other structures that reflect or absorb radio waves, for example, reception of GPS or GNSS signals may be significantly degraded. Degraded reception of satellite-based navigation signals due to various environmental effects, such as the presence of buildings, other structures or natural obstructions, may result in unreliable or inaccurate navigation solutions.